The scaling down of integrated circuit devices has created a need to incorporate high dielectric constant materials into capacitors and gates. The search for new high dielectric constant materials and processes is becoming more important as the minimum size for current technology is practically constrained by the use of standard dielectric materials. Dielectric materials containing alkaline earth metals can provide a significant advantage in capacitance compared to conventional dielectric materials. For example, the perovskite material SrTiO3 has a reported bulk dielectric constant of up to 500.
Unfortunately, the successful integration of alkaline earth metals into vapor deposition processes has proven to be difficult. For example, although atomic layer deposition (ALD) of alkaline earth metal diketonates has been reported, these metal diketonates have low volatility, which typically requires that they be dissolved in organic solvent for use in a liquid injection system. In addition to low volatility, these metal diketonates generally have poor reactivity, often requiring high substrate temperatures and strong oxidizers to grow a film, which is often contaminated with carbon. Other alkaline earth metal sources, such as those including substituted or unsubstituted cyclopentadienyl ligands, typically have poor volatility as well as low thermal stability, leading to undesirable pyrolysis on the substrate surface.
New sources and methods of incorporating high dielectric materials are being sought for new generations of integrated circuit devices.